Machines often use one or more hydraulic actuators to accomplish a variety of tasks. These actuators are fluidly connected to pumps on the machine that provide pressurized fluid to chambers within the actuators. As the pressurized fluid moves into or through the chambers, the pressure of the fluid acts on hydraulic surfaces of the chambers to effect movement of the actuator and a connected work tool or implement. When the pressurized fluid is drained from the chambers it returns to a low pressure sump on the machine. A significant amount of energy may be required to operate a plurality of hydraulic actuators. In order to increase efficiency, some machines use regenerative systems to recover energy during the operation of such hydraulic systems.
Mobile machines also use some type of propulsion system to drive the machine such as a hydraulic system or a hydrostatic system. These propulsion systems may include a regenerative system to increase the efficiency of operation.
Energy that is recovered by a regenerative system may be stored in various types of energy storage devices or systems. For example, energy recovered in a hydraulic system is often stored in a hydraulic accumulator, and energy stored in an electrical system is often stored in a battery or capacitor system. However, certain inefficiencies exist when storing energy as well as when subsequently converting it back into usable power. Accordingly, some machines share energy between systems. U.S. Pat. No. 7,472,546 discloses a hydrostatic regenerative braking system that stores energy in a hydraulic accumulator. The stored energy may be subsequently used by directing pressurized hydraulic fluid as desired to propel the machine or to drive a secondary steering system.